Agrichemical contamination is a growing concern since more than 12 different pesticides have been found in the ground water in at least 25 states in this country alone. Studies have shown that pesticide residues in ground water are increasing and are particularly severe where agronomic and horticultural crops are grown in permeable sandy soils or in locations which receive heavy rainfall. Among the chemicals which are particularly troublesome are herbicides such as bromacil, atrazine, metribuzin, dicamba and metolachlor, nematicides such as aldicarb, fungicides such as triforine, penconazole and insecticides such as bendiocarb, diazinone, chloropyrophos and ethion, which have been found in drinking water. Hence, there is an acute need to restrict the downward movement of pesticides, herbicides and other organic pollutants in the soil without reducing their agricultural efficacy.
Control of agrichemical leaching is a complex art which depends on many factors including rainfall, soil acidity and type, as well as plant tolerance. Various solutions to the problem have been proposed including controlled release formulations and encapsulated suspensions of the harmful active chemical. Surfactants have been employed for restricting the downward movement of urea herbicides such as diuron, linuron and monuron (see Weeds, by D. E. Bayer, Vol. 15, pages 249-252, 1967). The mobility of metribuzin in the soil has been reduced by the use of polyvinyl alcohol polymers, as discussed by C. L. McCormick and M. M. Fooladi, (1980) (Controlled Activity Polymers with Labile Bonds to Pendent Metribuzin in Controlled Release of Bioactive Materials, R. Baker, Academic Press, New York, pages 317-330). However, it was found that metribuzin formed covalent linkages with the polyvinyl alcohols which resulted in hindering its release from the alcoholic polymer for plant uptake. Certain pine craft lignins have shown some decrease in the leaching losses of atrazine and 2,4-D (see Weed Science, E. P. Dunigan and T. Macintosh, 1971, Volume 29 pages 279-282 and Controlled Release Technologies: Methods, Theory and Application by H. T. Dellicolli, 1980, Volume II, C. R. C. Press, Boca Raton, Fla., pages 225-234). Several other leaching inhibitors have been proposed; however, the chemicals currently used to inhibit downward movement have been found to be highly specific to certain chemical types and do not extend generally to plant treating agrichemicals of different chemical classes.
Accordingly, it is an object of this invention to provide a leach inhibiting chemical which is more broadly effective in preventing or inhibiting downward movement of various plant treating materials.
Another object of this invention is to provide an economically produced chemical which prevents or minimizes the movement of toxic chemicals in the soil and retains the plant treating agent in the root or immediate surrounding area of the soil where it is applied and where it is most effective.
Another object of this invention is to provide a leach inhibiting chemical composition which permits more efficient use of a crop treating agent in reduced amounts and which prevents or minimizes contamination of the aquasystem.
These and other objects of the invention will become apparent to one skilled in the art from the following description and disclosure.